Progressively erasing and updating storage tube for ecg. display

ABSTRACT

An ECG. display on which the ECG. signal appears on a storage cathode-ray tube. Instead of erasing the entire display at the end of each line trace, only a short segment at the leftmost side of the trace is erased. As the new sweep begins, the old trace is progressively erased. In effect, an &#39;&#39;&#39;&#39;erase&#39;&#39;&#39;&#39; signal precedes the write beam as it moves from left to right across the screen. The arrangement permits display of each ECG. waveform for the maximum time period.

United States Patent 7/1970 Pearson..... 12/1967 Yaggy etal.

OTHER REFERENCES Roland, Screen for Dock Trace Tube, 8/65, pp. 422- 423,IBM Technical Disclosure Bulletin, Vol. 8, No. 3

Primary Examiner-Rodney D. Bennett, Jr.

Assistant Examiner-N. Moskowitz Attorneys-William C. Nealon, Noble 8.Williams, Robert J.

Bird and Amster & Rothstein [72] Inventor Barouh V. Berkovitz NewtonHighlands, Mass. 21 Appl. No. 872,231 [22] Filed Oct. 29, 1969 [45]Patented Dec. 14, 1971 [73] Assignee American Optical CorporationSouthbridge, Mass.

[54] PROGRESSIVELY ERASING AND UPDATING STORAGE TUBE FOR ECG. DISPLAY 11Claims, 4 Drawing Figs.

[52] US. Cl 315/12, 313/68, 178/72 (51] Int. Cl H01] 29/41 [50] Field ofSearch 315/12, 28; 313/65 TP, 68 B, 68 A, 89, 92,108 B; 178/72 [56]References Cited UNITED STATES PATENTS 3,214,631 10/1965 Anderson 313/68A PRIOR ART 50-1 ERASE PULSE GENERATOR coma/non coumnon common DETEOTOR.5 (1.5) (8.5) a; 54 oe-2 1 56-9 1 oo-lo 60 lov.

uomzonm 64' uomzotm Lev. T0 HORIZONTAL an: swear DEFLEGTIIG PLATE comotcrurmon mum Patented Dec. 14, 1971 3,628,081

l2b I2b I 2 ELECTRONIC CONTROL P 0 Rm F/GZ CIRCUITS 24b F/G/ PRIOR ARTFIG. 3

COMPARATOR COMPARATOR (1.5) (0.5)

56-9 ss-lo IOV. HORIZONTAL 4RoR|zoRTRL ov. To RomzoRm RATE swEEP*DEFLECTINGPLAIE CONTROL GENERATOR AMPLIFIER F76. 4 VIDEO Rm 72 REcElvERDISPLAY VIDEO H (164 TRANSMITTER I VIDEO VIDEO 7H RECEIVER DISPLAYINVI'INI'UH.

BAROUH V. BERKOVITS M RM PROGRESSIVELY ERASING AND UPDATING STORAGE TUBEFOR ECG. DISPLAY This invention relates to electrocardiographic ECG.displays, and more particularly to ECG. displays which incorporatestorage cathode-ray tubes.

On a typical ECG. display, after each waveform appears it persists foronly a short time interval. As the trace moves from left to right acrossthe screen, only the last few waveforms can be seen. It would bedesirable to have a longer persistance for each waveform so that eachnew waveform could be observed with preceding waveforms.

It has been proposed to utilize a storage cathode-ray tube for thispurpose. With such a tube, it is possible to provide an ECG. display inwhich all information which appears on the display persists until theend of each line trace. During the flyback, the entire line is erasedprior to the start of a new trace. Although this arrangement does permitthe waveforms at the end of each line trace to be observed along withpreceding waveforms, it is apparent that the same is not true of thewaveforms at the beginning of each trace-when they are formed there areno other waveforms on the screen.

It is an object of my invention to provide a display for a repetitivesignal in which every signal, after it is formed on the display,persists for an extended time interval.

It is another object of my invention to provide such a display for anECG. monitoring system.

Briefly, in accordance with the principles of my invention, aconventional split-screen storage cathode-ray tube is modified to permitthe progressive erasing of the display preceding each new trace. in theordinary storage tube, there is a transparent backplate sandwichedbetween the faceplate and the phosphor layer. The backplate isordinarily held at a high potential; to erase the display, a negativepulse is applied to the backplate. In the split-screen type tube,instead of a single continuous backplate, there are upper and lowerbackplate sections which are electrically isolated from each other. Ineffect, the backplate can be considered to have a horizontal dividingline along the center of the screen. When either backplate section ispulsed, the respective upper or lower half of the screen display iserased.

In accordance with the principles of my invention, instead of twohorizontal backplate sections, the tube includes a plurality ofelectrically isolated vertical sections. Each of these sections can bepulsed individually. When a vertical backplate section is pulsed, itcauses the erasure of only that part of the screen adjacent to theparticular section. To control a progressive erasure which precedes thewrite beam, the vertical backplate sections are pulsed in successionfrom left to right, with any section being pulsed just before the writebeam reaches it.

It is a feature of my invention to provide a storage cathoderay tubehaving a plurality of electrically isolated backplate sections, each ofwhich when pulsed causes the corresponding section of the display to beerased.

It is another feature of my invention to provide a circuit for pulsingeach backplate section just prior to the write beam reaching thecorresponding portion of the phosphor layer.

Further objects, features, and advantages of my invention will becomeapparent upon consideration of the following detailed description inconjunction with the drawing, in which:

F IG. 1 depicts schematically the prior art split-screen storagecathode-ray tube;

FIG. 2 depicts schematically the arrangement of the prior art backplateused in the cathode-ray tube of FIG. 1,

H6. 3 depicts schematically an illustrative embodiment of my invention;and

FIG. 4 illustrates a system which utilizes a modified storage tube of myinvention to the greatest advantage.

FIG. 1 depicts various elements in a conventional splitscreen storagecathode-ray tube 20. Sandwiched between faceplate and storage-targetlayer 14 are two halves of the storage-target backplate, 12a and 12b. Afront view of the backplate is shown in FIG. 2. The two sections 12a and12b are electrically isolated from each other. The cathode-ray tubeincludes a write gun l8 and two flood guns 22a and 22b. The two floodguns, as is known in the art, control the storage of the display. Theentire cathode-ray tube is contained in glass envelope 16. Electroniccontrol circuits 26 control the storage and erasure of the display oneither half of the screen. When either of conductors 24aand 24bisnegatively pulsed, the display on the respective upper and lower half ofthe screen is erased. Additional control signals for the cathode-raytube are transmitted over cable 28. The operation and design of storagecathode-ray tubes in general, and split-screen tubes in particular, arewell known to those skilled in the art. A complete description of thesubject matter can be found in a booklet entitled Storage Cathode-RayTubes And Circuits" by Chuck DeVere, published in 1968 by Tektronix,lnc.

FIG. 3 depicts an illustrative embodiment of my invention; only thoseelements which are different from, or in addition to, those in FIGS. 1and 2 are depicted in the drawing. It is to be understood, for example,that although only the storagetarget backplate consisting of verticalsegments 30-1 through 30-10 is shown, the storage tube of the system ofFIG. 3 includes a phosphor layer 14, a faceplate 10, the variouselectron guns, etc.

Instead of utilizing a horizontally split backplate as shown in FIG. 2,the system of FIG. 3 utilizes vertically split backplate. In theillustrative embodiment of the invention, the screen is divided into 10electrically isolated segments 30-1 through 30- 10. The output ofrespective one of gates 50-1 through 50-10 is extended to each of thebackplate sections. One input of gate 50-1 is connected to the output offlyback detector 54. One input of each of gates 50-2 through 50-10 isconnected to the output of a respective one of comparators 56-2 through56-10. The other input of each of the ten gates is connected to theoutput of erase pulse generator 52. When the erase pulse generator istriggered, it generates an erase pulse 53 at its output. When the erasepulse is generated only one of gates 50-1 through 50-10 is operative,and the erase pulse is transmitted to the respective vertical backplatesegment.

The output flyback detector 54 and the outputs of all of comparators56-2 through 56-10 are connected to respective inputs of OR-gate 58.When any one of the flyback detector or the nine comparators operates,the OR gate triggers the erase pulse generator. At this time the erasepulse is transmitted to the respective one of the vertical backplatesegments.

The electronic control circuits include a horizontal rate controlcircuit 62 with a manually adjustable potentiometer 60. The setting ofthe potentiometer determines the horizontal sweep rate. The output ofthe horizontal rate control circuit 62 is extended to the input ofhorizontal sweep generator 64. A sawtooth waveform appears at the outputof the sweep generator. This sawtooth, extending between zero and l0volts in a time period corresponding to the setting of potentiometer 60,is directed to the horizontal deflecting plate amplifier, which in turnderives a sawtooth waveform sufi'lcient in magnitude to drive theelectron write beam across the screen.

The sawtooth waveform is also extended to the input of flyback detector54 and the input of each of the nine comparators 56-2 through 56-10.Flyback detector 54 detects the flyback following each sweep across thetube. The output of the detector is energized and an erase pulse istransmitted through gate 50-1 to backplate segment 30-1. Thus duringflyback, the first 10 percent of the display on the screen is erased.The first 10 percent of the display is erased prior to the start of anew sweep. The remaining percent of the previous trace is stilldisplayed.

Each comparator energizes its output when the positively slopingsawtooth voltage reaches a respective level. Comparator 56-2 energizesits output when the sawtooth waveform has risen to 0.5 volts. At thistime, the new trace is in the middle of the first segment 30-1. With theenergization of comparator 56-2, that portion of the old trace beneathsegment 30-2 is erased. As the new trace continues, the sawtoothwaveform continues to rise in voltage. When it has risen to 1.5 volts,

comparator 56-3 (not shown) energizes its output. At this time, the newtrace is in the middle of segment 30-2 and the old trace is in segment30-3 is erased.

Similarly, when the new trace is in the middle of segment 30-8, thesawtooth waveform is at a level of 7.5 volts. At this time the old traceadjacent to segment 30-9 is erased. Finally, when the new trace is inthe middle of segment 30-9, comparator 56-10 operates and the lastpercent of the old trace is erased.

It is apparent that, as the write beam sweeps across the face of thecathode-ray tube. that portion of the old trace immediately ahead of thewrite beam is erased. The erased portion of the display ahead of thewrite beam in the arrangement of FIG. 3 varies between 5 and percent ofthe width of the entire display. For example, when the new beam reachesthe middle of section 30-2, section 30-3 is pulsed and the old trace isthen erased along the remaining latter half of section 30-2 and thewidth of section 30-3, a total distance corresponding to l5 percent ofthe entire width of the display. On the other hand, just before thewrite beam reaches the midpoint of section 30-2, the only erased portionof the display is the latter half of section 30-2, a width correspondingto 5 percent of the entire display. It is apparent that if more verticalsections are used, the range of the width of the erased portion can benarrowed. For example, with vertical segments, the range varies between2.5 and 7.5 percent of the entire display. Similarly, it is possible topulse a vertical section which is two or more sections ahead of thewrite beam in order that a larger erased portion of the display precedethe write beam. This can be accomplished in the system of FIG. 3 simplybe increasing the slope and peak level of the sawtooth at the output ofsweep generator 64.

Storage tubes in general are relatively expensive. The smaller thedisplay area, the cheaper the tube. The arrangement of FIG. 4illustrates how a very small storage tube can be utilized in an ECG.display system. Storage tube 70 is of the type depicted in FIG. 3. Tothe face of the tube there is attached a TV scanner 72. The resulting TVsignal is applied to the input of video transmitter 74, which in turn isconnected to a plurality of video receivers 703-1 through 76-N. Eachvideo receiver controls a display on a respective one of displays 78-1through 78-N. The size of each video display can be much larger than thesize of the display on the screen of storage tube 70. The arrangement ofFIG. 4 is particularly advantageous when it is necessary to direct thesame ECG. signal to a number of stations. Rather than to use avertically segmented storage tube at each station, it is only necessaryto provide a single such tube together with a relatively inexpensivevideo receiver and display at each station.

In the system of FIG. 4, the storage tube does not provide a visualdisplay, since the visual display is covered up" by TV scanner 72.Rather than to provide two separate elements 70 and 72, it is possibleto utilize a single storage tube with a read" capability. In such acase, as a trace is stored (with or without a visual output), it iscontinuously read with the resulting video signal being forwarded to allof the video receiver-display stations.

It will also be obvious to those skilled in the art that otherarrangements can be used for generating an "erase" signal which precedesthe write" signal as it sweeps across the storage tube. For example, inthe conventional storage tube the flood guns cause electrons to bombardthe entire screen. By providing additional horizontal deflecting plates,for example, it is possible to momentarily stop the flooding of thescreen along a particular vertical section. In such a case, that portionof the trace corresponding to the section which is no longer floodedwill be erased.

Although the invention has been described with reference to pa ticularembodiments. it is to be understood that these embodiments are merelyillustrative of the application of the principles of the invention.Numerous modifications may be made therein and other arrangements may bedevised without departing from the spirit and scope of the invention.

What I claim is: I. In a storage cathode-ray tube system in which awrite beam sweeps across the face of a storage cathode-ray tube in onedirection, the improvement comprising means for erasing the storedsignal contained within any one ofa plurality of sections of the displayperpendicular to said one direction, and means for sequentially erasingthe display in successive sections in the same direction in which saidwrite beam sweeps across the face of the tube.

2. An improved storage cathode-ray tube system in accordance with claim1 wherein said erasing means controls the erasure of the display in anyone of said sections when the write beam is in the preceding section inthe direction of the sweep of said write beam across the face of saidtube.

3. An improved storage cathode-ray tube system in accordance with claim2 wherein said erasing means includes a tube backplate segmented into aplurality of sections perpendicular to said one direction and means forapplying an erase pulse to any one of said segments individually.

4. An improved storage cathode-ray tube system in accordance with claimI wherein said erasing means includes a tube backplate segmented into aplurality of sections perpendicular to said one direction and means forapplying an erase pulse to any one of said segments individually.

5. An improved storage cathode-ray tube system in accordance with claim4 wherein said segmented backplate sections are sequentially pulsed at arate determined by the time required for said write beam to sweep acrossthe face of the cathode-ray tube.

6. In a storage cathode-ray tube having a source of a write beam whichsweeps across the face of the tube and a backplate which when pulsederases the stored signal adjacent to it, the improvement comprising thearrangement of said backplate in a plurality of sections eachperpendicular to the direction in which said write beam sweeps acrossthe face of the tube, and means connected to each of said backplatesections for transmitting thereto a pulse for erasing only that portionof the stored signal adjacent to the particular section.

7. An ECG. signal storage system comprising a storage cathode-ray tubein which a write beam sweeps across the face of the tube, means forcontrolling the deflection of said write beam in a directionperpendicular to the direction of said sweep in accordance with themagnitude of an ECG. signal, and means for continuously erasing only aportion of the signal stored in said cathode-ray tube in the directionof said sweep in front of said write beam.

8. A ECG. signal storage system in accordance with claim 7 wherein saiderasing means includes a backplate on said cathode-ray tube segmentedinto a plurality of sections perpendicular to the direction of saidsweep and means for applying erase pulse to successive segments of saidbackplate sequentially in the direction of said sweep.

9. An ECG. signal storage system in accordance with claim 8 wherein saidsegmented backplate sections are sequentially pulsed at a ratedetermined by the time required for said write beam to sweep across theface of said cathode-ray tube.

10. A ECG. signal storage system in accordance with claim 6 wherein therate at which the storage signal is erased in front of said write beamis dependent upon the time required for said write beam to sweep acrossthe face of the cathode-ray tube.

11. In a storage cathode-ray tube used for storing a ECG. signal andhaving a source of a write beam which sweeps across the face of the tubeand is deflected in accordance with the magnitude of an ECG. signal, anda backplate which when pulsed erases the stored ECG. signal adjacent toit, the improvement comprising the arrangement of said backplate in aplurality of sections each perpendicular to the direction in which saidwrite beam sweeps across the face of the tube, and means connected toeach of said backplate sections for transmitting thereto a pulse forerasing only that portion of the stored ECG. signal adjacent to theparticular section.

1. In a storage cathode-ray tube system in which a write beam sweepsacross the face of a storage cathode-ray tube in one direction, theimprovement comprising means for erasing the stored signal containedwithin any one of a plurality of sections of the display perpendicularto said one direction, and means for sequentially erasing the display insuccessive sections in the same direction in which said write beamsweeps across the face of the tube.
 2. An improved storage cathode-raytube system in accordance with claim 1 wherein said erasing meanscontrols the erasure of the display in any one of said sections when thewrite beam is in the preceding section in the direction of the sweep ofsaid write beam across the face of said tube.
 3. An improved storagecathode-ray tube system in accordance with claim 2 wherein said erasingmeans includes a tube backplate segmented into a plurality of sectionsperpendicular to said one direction and means for applying an erasepulse to any one of said segments individually.
 4. An improved storagecathode-ray tube system in accordance with claim 1 wherein said erasingmeans includes a tube backplate segmented into a plurality of sectionsperpendicular to said one direction and means for applying an erasepulse to any one of said segments individually.
 5. An improved storagecathode-ray tube system in accordance with claim 4 wherein saidsegmented backplace sections are sequentially pulsed at a ratedetermined by the time required for said write beam to sweep across theface of the cathode-ray tube.
 6. In a storage cathode-ray tube having asource of a write beam which sweeps across the face of the tube and abackplate which when pulsed erases the stored signal adjacent to it, theimprovement comprising the arrangement of said backplate in a pluralityof sections each perpendicular to the direction in which said write beamsweeps across the face of the tube, and means connected to each of saidbackplate sections for transmitting thereto a pulse for erasing onlythat portion of the stored signal adjacent to the particular section. 7.An ECG. signal storage system comprising a storage cathode-ray tube inwhich a write beam sweeps across the face of the tube, means forcontrolling the deflection of said write beam in a directionperpendicular to the direction of said sweep in accordance with themagnitude of an ECG. signal, and means for continuously erasing only aportion of the signal stored in said cathode-ray tube in the directionof said sweep in front of said write beam.
 8. An ECG. signal storagesystem in accordance with claim 7 wherein said erasing means includes abackplate on said cathode-ray tube segmented into a plurality ofsections perpendicular to the direction of said sweep and means forapplying erase pulses to successive segments of said backplatesequentially in the direction of said sweep.
 9. An ECG. signal storagesystem in accordance with claim 8 wherein said segmented backplatesections are sequentially pulsed at a rate determined by the timerequired for said write beam to sweep across the face of saidcathode-ray tube.
 10. An ECG. signal storage system in accordance withclaim 6 wherein the rate at which the storage signal is erased in frontof said write beam is dependent upon the time required for said writebeam to sweep across the face of the cathode-ray tube.
 11. In a storagecathode-ray tube used for storing a ECG. signal and having a source of awrite beam which sweeps across the face of the tube and is deflected inaccordance with the magnitude of an ECG. signal, and a backplate whichwhen pulsed erases the stored ECG. signal adjacent to it, theimprovement comprising the arrangement of said backplate in a pluralityof sections each perpendicular to the direction in which said write beamsweeps across the face of the tube, and means connected to each of saidbackplate sections for transmitting thereto a pulse for erasing onlythat portion of the stored ECG. signal adjacent to the particularsection.